e-licktronic Forum

Hi fellow Nava builders,

I've recently finished my build and was able to fix all remaining voice problems on my own thanks to the rich history of posts in this forum. (With the exception of those damn mux_sh boards which I gave up on and ordered a set of replacements from Klanggenerator which work flawless) I only have one problem remaining now and that is my crash which is way to loud in general and is constantly getting louder and thereby more distorted until it's just some crackling sound. It starts out sounding halfway normal and builds up over time. I'm suspecting it has something to do with the vca of this voice, but i'm a little bit out of my comfort zone here and also have no oscilloscope at hand to debug further.

Things I've tried so far:

• - Swapped all voice ics with the ride which is working just fine - The problem remains.
  - Swapped the eprom to the ride - Eprom seems fine as it plays correctly in the ride voice.
  - Swap IC112 and IC113 - No changes
  - Measured all pcb traces for continuity - Everything fine
  - Measured all resistors in voice - All within tolerance
  - Inspected all solder points and reflowed suspicious ones. - No dice..

I've uploaded a soundclip here:
https://voca.ro/babpKf69hiP

As you can hear it starts out sounding ok and gets louder at about 01:30. I turned the volume of the voice way down for the recording to not clip the recording device. The voice is extremely loud compared to the other ones even when not distorting. I'm out of ideas and would appreciate some input.

Cheers,
Chris

Ok, so after building a DSO150 oscilloscope and a bit of debugging i narrowed it down to the 2SA798 in Q70. So i swapped the one from Q68 over to verify my suspicion and the crash started to work as it should. Vincent said he'll send me a replacement so case closed

The takeaway here: Always test your transistors before soldering them if you can!